410 PHYSIOLOGY. 



and intestinal peristalsis. Pituitary extract when given, increases 

 calcium in the blood. Adrenal extract causes the blood to retain 

 calcium. Now, tetany can ensue in lactation, in rickets, in pregnancy, 

 and from operations on the thyroid, involving the parathyroids. There 

 is a juvenile tetany, and a tetany due to gastro-intestinal disorder. 

 Eclampsia and paralysis agitans have been referred to changes in the 

 parathyroid. 



THE SPLEEN. 



The spleen is deeply placed in the left hypochondrium. Its 

 shape is a half-ovoid. Its consistency is comparatively soft, and its 

 color is purplish. Its external convex surface is in contact with the 

 diaphragm opposite the three or four lower ribs. Its internal sur- 

 face is applied to the fundus of the stomach, to which it adheres by 

 the gastro-splenic omentum. In the middle of the internal surface 

 of the spleen there is a slight groove, the hilus, where the artery and 

 nerves enter. The spleen usually is five inches in length, four inches 

 in breadth, and from one to one and one-half inches thick. It has 

 two coats : the outer serous and the inner fibre-elastic. 



The spleen when torn has a deep reddish-black, pulpy appear- 

 ance, resembling coagulated blood. This splenic pulp may be 

 removed from the spleen by maceration, leaving a spongy mass com- 

 posed of splenic blood-vessels associated with numerous trabeculae 

 of fibro-elastic tissue. Adhering to the side of the smallest arteries 

 of the spleen are small, rounded, whitish bodies, the corpuscles of 

 Malpighi, one-thirtieth to one-sixtieth of an inch in diameter. The 

 splenic pulp contains red blood-corpuscles, granular corpuscles re- 

 sembling lymphocytes in appearance, having an amoeboid movement, 

 and red corpuscles undergoing disintegration. 



Function. The extirpation of the spleen leaves life and health 

 intact in animals and in man. All that results is a more or less pro- 

 nounced hypertrophy in all the lymphatic ganglia of the body. 



Direct irritation of the spleen, the direct or reflex irritation of 

 the medulla oblongata, the application of ice-water to the left hypo- 

 gastrium, and quinine cause a diminution of the spleen by contrac- 

 tion of the muscles of the capsule and trabecula. The spleen is con- 

 gested during digestion, and when the portal circulation is interfered 

 with, and in a great number of infectious diseases, notably typhoid 

 and malarial fevers. The spleen is supposed by some to manufac- 

 ture white blood-corpuscles, and this manufacturing reaches a pro- 

 nounced activity when the organ is hypertrophied, as in leuco- 



